Effects of Lowering PEEP Below Recommended Values in Pediatric ARDS

Pediatric patients with acute respiratory distress syndrome (ARDS) managed with positive end expiratory pressure (PEEP) levels below those recommend by the ARDS Network PEEP/fraction of inspired oxygen (FiO₂) titration table may have higher mortality rates, even after adjustment for covariates, according to a study published in the American Journal of Respiratory and Critical Care Medicine. 

The study researchers analyzed 4 previously published data sets of pediatric patients placed on invasive mechanical ventilation diagnosed with pediatric ARDS (PARDS). Data from 2 of the studies were gathered retrospectively from children admitted to the pediatric intensive care unit at Children’s Hospital, Los Angeles. 

One of 2 prospective studies contained data from children admitted to the Children’s Hospital of Philadelphia, and the final prospective study contained data from 8 hospitals included in the Collaborative Pediatric Critical Care Research Network.

The purpose of the study was to evaluate whether a higher mortality was associated with PEEP levels lower than those recommended by the ARDS Network table compared with those at or above the recommendations in pediatric patients diagnosed with ARDS placed on invasive mechanical ventilation.

Researchers identified a total of 1134 patients from the 4 identified patient datasets. Pressure control was the mode of conventional ventilation in 63% of patients, and 36.7% were placed on pressure-regulated volume control. The number of patients managed on PEEP at levels lower, at, or above the ARDS Network protocol recommendations were found to be 302 (26.6%), 351 (34.7%), and 394 (34.7%), respectively. Patients with ARDS who did not receive adequate PEEP on day 1 were 7.7% (n=87) of the total patient population.

Researchers found an overall higher mortality rate in pediatric patients managed with PEEP levels lower than those recommended based on the ARDS Network protocol (26.5% vs 14.9%, P <.001). 

In an unadjusted analysis of the data, researchers found a higher mortality within the first 24 hours of PARDS in individuals managed with PEEP less than recommended by the protocol for a given FiO₂, while a higher survival rate was associated with PEEP management levels 1 to 4 cm of water above the protocol recommendations. 

Researchers then looked at variables that were associated with lower than recommended levels of PEEP for a given FiO₂ and found all the following to be related to the lower level of PEEP (P <.05): Hispanic race, dataset, lower initial and 24-hour partial pressure of oxygen/FiO₂ ratio and worse partial pressure of oxygen/FiO₂ group, higher oxygen intake, lower use of inotropes, sepsis, higher Pediatric Risk of Mortality III score, and higher ventilator driving pressure.

Patients who had hypoxemia with more severe illness had a higher incidence of lower PEEP relative to FiO₂. After data were controlled for confounding variables (PF ratio during first 24 hours, inotrope use, immunodeficiency, stem cell transplant, Pediatric Risk of Mortality III score, nitric oxide, driving pressure, and dataset), these patients were also more likely to die (odds ratio [OR], 2.05; 95% CI,1.32-3.17). 

After adjusting for covariates and propensity of lower PEEP use, lower PEEP relative to FiO₂ was found to be independently associated with a higher mortality rate (OR 2.0; 95% CI,1.24-3.22).

Researchers concluded that even after covariate adjustment, an overall higher mortality rate was associated with PARDS management with PEEP levels lower than those recommended by the ARDS Network PEEP/FiO₂ protocol. The authors were also careful to state that, although this study could not infer a causal relationship between management of PARDS based on the ARDS Network PEEP/FiO₂ protocol and a higher survival rate, the data do show a high plausibility. 

Clinicians should strongly consider following the PEEP/FiO₂ ARDS Network protocol when caring for pediatric patients despite the absence of a pediatric-specific protocol, as study results shows a higher mortality when PEEP levels are lower than those recommended in the ARDS Network protocol.

Reference

Khemani RG, Parvathaneni K, Yehya N, Bhalla AK, Thomas NJ, Newth CJL. PEEP lower than the ARDS network protocol is associated with higher pediatric ARDS mortality [published online January 26, 2018]. Am J Respir Crit Care Med. doi:10.1164/rccm.201707-1404OC